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Variation in reproductive characteristics of colonies of the freshwater bryozoan Cristatella mucedo
- UOTILA, LAURA, JOKEL, JUKKA
- Freshwater biology 1995 v.34 no.3 pp. 513-522
- clones, freshwater, larvae, lotic systems, reproductive traits, sexual reproduction, Finland
- 1. We studied relationships between different forms of reproduction and local variation in the reproductive state of colonies of a common freshwater bryozoan Cristatella mucedo Cuvier (Bryozoa: Phylactolaemata). Four sampling locations in central Finland, including both lotic and lentic habitats, were sampled by scuba diving. The traits studied were occurrence of sexual larvae, colony size, number of resting stages (statoblasts) and number of zooids. 2. While 76.9% of the sampled colonies carried statoblasts at the time of sampling, only 4.5% of the colonies were brooding sexual larvae. Most of the colonies were relatively small with a mean colony size of 16.6 mm. 3. In colonies brooding larvae, the number of statoblasts was positively correlated with the number of larvae. We did not detect a colony size threshold for sexual reproduction or formation of statoblasts. Colonies carrying statoblasts had a lower number of zooids per unit dry weight. 4. We found significant variation in reproductive traits of colonies among the sampling locations, and among lotic and lentic habitats. The observed phenotypic differences may reflect broadly distributed, phenotypically plastic clones. Differences in clonal composition of local populations cannot, however, be ruled out and factors that may provide clonal diversity are discussed.